Weld collet

ABSTRACT

A collet member for a colleting fixture includes a monolithic collet body having a clamping block engaging outer wall and a workpiece engaging inner wall extending circumferentially between first and second end walls, with each of the outer wall, the inner wall, and the first and second end walls extending axially between first and second radial walls to enclose at least one internal cavity.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. Design patent applicationSer. No. 29/662,200, filed on Sep. 4, 2018, for WELD COLLET, the entiredisclosure of which is fully incorporated herein by reference.

BACKGROUND

The use of rigid collets for holding tubing and other workpieces duringwelding operations has often been preferred over split or adjustablecollets, due to the ability of the rigid collets to minimizemisalignment between the workpieces being welded (e.g., due to thermalstresses). Referring to FIG. 1, a conventional rigid collet (shown, forexample, in U.S. Pat. No. 4,868,367, the entire disclosure of which isincorporated herein by reference) includes a pair of solid,semi-cylindrical collet members 48, 50 retained in opposed clamp halvesor clamping blocks 22, 24 of a clamp assembly 10. As shown, the colletelements define a cylindrical interior clamping surface 56 for securelypositioning and retaining a cylindrical workpiece (e.g. a tube). Theextended cylindrical clamping surface and solid collet construction,while providing for rigid, secure colleting of the workpieces, maycontribute to increased heat transfer away from the workpieces,particularly for workpiece materials having high thermal conductivity,such as copper.

SUMMARY

According to an exemplary aspect of the present application, a colletmember for a colleting fixture includes a monolithic collet body havinga clamping block engaging outer wall and a workpiece engaging inner wallextending circumferentially between first and second end walls, witheach of the outer wall, the inner wall, and the first and second endwalls extending axially between first and second radial walls to encloseat least one internal cavity.

According to another exemplary aspect of the present application, acolleting fixture includes first and second clamping blocks and firstand second collet members secured to corresponding ones of the first andsecond clamping blocks. The first and second clamping blocks arejoinable such that the first and second collet members together define aworkpiece engaging collet. At least one of the first and second colletmembers comprises a monolithic collet body including a clamping blockengaging outer wall and a workpiece engaging inner wall extendingcircumferentially between first and second end walls, each of the outerwall, the inner wall, and the first and second end walls extendingaxially between first and second radial walls to enclose at least oneinternal cavity.

According to another exemplary aspect of the present application, amethod of clamping a workpiece for a welding operation is contemplated.In one such exemplary method, first and second collet members aresecured to first and second clamping blocks. The first and secondclamping blocks are joined such that the first and second collet memberstogether define a workpiece engaging collet. At least one of the firstand second collet members comprises a monolithic collet body including aclamping block engaging outer wall and a workpiece engaging inner wallextending circumferentially between first and second end walls, witheach of the outer wall, the inner wall, and the first and second endwalls extending axially between first and second radial walls to encloseat least one internal cavity. The workpiece is engaged between innerwalls of the first and second collet members. A cooling fluid iscirculated through the at least one internal cavity of the at least oneof the first and second collet members.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and benefits will become apparent to those skilled inthe art after considering the following description and appended claimsin conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a fixture for holding a workpiece;

FIG. 2 is a perspective view of a collet for a workpiece holdingfixture, in accordance with an exemplary embodiment of the presentapplication;

FIG. 3 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 4 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 5 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 6 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 7 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 8 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 9 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 10 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 11 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 12 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 13 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 14 is a perspective view of another collet for a workpiece holdingfixture, in accordance with another exemplary embodiment of the presentapplication;

FIG. 14A is a perspective view of the collet of FIG. 14, with a portionof the rear wall cut away to illustrate internal features of the collet;and

FIG. 15 is a perspective view of another collet for a workpiece holdingfixture, with a portion of the rear wall cut away to illustrate internalfeatures of the collet.

DETAILED DESCRIPTION

While various inventive aspects, concepts and features of the inventionsmay be described and illustrated herein as embodied in combination inthe exemplary embodiments, these various aspects, concepts and featuresmay be used in many alternative embodiments, either individually or invarious combinations and sub-combinations thereof. Unless expresslyexcluded herein all such combinations and sub-combinations are intendedto be within the scope of the present inventions. Still further, whilevarious alternative embodiments as to the various aspects, concepts andfeatures of the inventions--such as alternative materials, structures,configurations, methods, circuits, devices and components, software,hardware, control logic, alternatives as to form, fit and function, andso on—may be described herein, such descriptions are not intended to bea complete or exhaustive list of available alternative embodiments,whether presently known or later developed. Those skilled in the art mayreadily adopt one or more of the inventive aspects, concepts or featuresinto additional embodiments and uses within the scope of the presentinventions even if such embodiments are not expressly disclosed herein.Additionally, even though some features, concepts or aspects of theinventions may be described herein as being a preferred arrangement ormethod, such description is not intended to suggest that such feature isrequired or necessary unless expressly so stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure, however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Still further,exemplary or representative values and ranges may be included to assistin understanding the present disclosure, however, such values and rangesare not to be construed in a limiting sense and are intended to becritical values or ranges only if so expressly stated. Parametersidentified as “approximate” or “about” a specified value are intended toinclude both the specified value and values within 10% of the specifiedvalue, unless expressly stated otherwise. Further, it is to beunderstood that the drawings accompanying the present application may,but need not, be to scale, and therefore may be understood as teachingvarious ratios and proportions evident in the drawings. Moreover, whilevarious aspects, features and concepts may be expressly identifiedherein as being inventive or forming part of an invention, suchidentification is not intended to be exclusive, but rather there may beinventive aspects, concepts and features that are fully described hereinwithout being expressly identified as such or as part of a specificinvention, the inventions instead being set forth in the appendedclaims. Descriptions of exemplary methods or processes are not limitedto inclusion of all steps as being required in all cases, nor is theorder that the steps are presented to be construed as required ornecessary unless expressly so stated.

The Detailed Description merely describes exemplary embodiments and isnot intended to limit the scope of the claims in any way. Indeed, theinvention as claimed is broader than and unlimited by the exemplaryembodiments, and the terms used in the claims have their full ordinarymeaning. For example, while specific exemplary embodiments in thepresent application describe collets for use with weld fixtures inorbital welding systems, one of more of the features described hereinmay additionally or alternatively be applied to other types of weldingsystems, or for use in other types of fixturing applications.Additionally, while the geometries and arrangements of many of thecollets described herein are such that their production is facilitatedby additive manufacturing, other manufacturing methods may be utilizedto fabricate collets having one or more of the features describedherein, such as, for example, stacked plate assembly, machining,welding, brazing, and casting (e.g., investment casting, sand casting,lost wax casting).

FIG. 2 illustrates an exemplary collet member 150 for use with a weldfixture (e.g., the exemplary fixture assembly 10 of FIG. 1). While theexemplary collet member 150 has a semi-cylindrical body 151, othercollet body shapes may alternatively be utilized (e.g., rectangular,hex-shaped). The collet body 151 includes a clamping block engagingouter portion (shown schematically at 152), a workpiece engaging innerportion (shown schematically at 154), and an intermediate portion (shownschematically at 153) extending radially between the outer portion 152and the inner portion 154. The exemplary collet member 150 also includesan outer radial flange 158 for abutting the exterior side (i.e. oppositethe weld side) of the clamping block to axially position the colletmember 150, and a radially extending fastener bore 159 for receiving afastener for affixing the collet member 150 to the clamping block.

According to an aspect of the present application, a collet member for aweld fixture may be configured to provide for reducing heat transferaway from a fixtured workpiece during welding. Referring to FIG. 2, inan exemplary embodiment, the inner portion 154 of the collet body 151may have a reduced thermal conductivity compared to the outer portion152 of the collet body, to reduce heat transfer from the workpiece. Inone such embodiment, the inner portion 154 of the collet body 151 may beprovided in a different material than the outer portion 152, having alower thermal conductivity. For example, the inner portion 154 of thecollet body 151 may comprise titanium alloys such as Ti-6A1-4V,zirconium and its alloys, nickel-base alloys such as Hastelloy C and X,Inconel alloy 625 and 718, and Monel alloy 400 and K-500, cobalt-basealloys such as Haynes 25 and CoCr derivatives, or any suitable materialhaving a relatively low thermal conductivity (e.g., less than 20 W/mK)and the outer portion 152 may comprise stainless steel, aluminum and itsalloys, copper and its alloys such as brass and bronze, or any suitablematerial having a higher thermal conductivity (e.g., greater than 20W/mK). Material compatibility may be a consideration when selectingmaterial pairs. The use of different materials may, for example, providefor cost efficiencies, and/or desirable variations in density, heatcapacity, and/or corrosion behavior/resistance. In another exemplaryembodiment, the inner portion 154 of the collet body 151 may have agreater material porosity (e.g., void volume fraction greater than about15%) than the outer portion 152, with the greater porosity providing fora reduced thermal conductivity.

The workpiece engaging inner portion material of the collet body mayadditionally or alternatively be configured to provide other desirableproperties, including, for example, increased elasticity, corrosionbehavior/resistance, and/or density.

While variations in materials or material properties in the colletmember may be accomplished by mechanically fixing outer radial and innerradial components together to form the collet body, according to anotheraspect of the present application, additive manufacturing may beutilized to produce a monolithic collet body having the desiredproperties across the radial thickness of the collet body. Examples ofadditive manufacturing techniques that may be utilized include, forexample: laser powder bed fusion (direct metal laser sintering or“DMLS,” selective laser sintering/melting or “SLS/SLM,” or layeredadditive manufacturing or “LAM”), electron beam powder bed fusion(electron beam melting or “EBM”), ultrasonic additive manufacturing(“UAM”), or direct energy deposition (laser powder deposition or “LPD,”laser wire deposition or “LWD,” laser engineered net-shaping or “LENS,”electron beam wire deposition). Providing the collet body as a single,monolithic component may eliminate assembly costs, reduce componentwear, reduce adverse effects from heat cycling, improve corrosionbehavior (galvanic effects, crevice, stress corrosion cracking), andreduce lead time to manufacture.

According to another aspect of the present application, heat transferaway from a fixtured workpiece may be reduced by reducing the materialmass of the collet member, and/or providing cavities or air gaps in thecollet member that impede thermal conduction. In one such embodiment,the intermediate portion 153 of the collet body 151 may include aplurality of rigid, radially extending members 155 (e.g., ribs, pins,fins, blades, etc.) extending between the outer portion 152 and theinner portion 154 to define a plurality of cavities 156.

FIG. 3 illustrates an exemplary collet member 250 including a colletbody 251 having an outer semi-cylindrical wall portion 252 forengagement with a clamping block, an inner semi-cylindrical wall portion254 for engaging a workpiece (e.g., a tube end or other cylindricalworkpiece), and a plurality of ribs 255 extending from the outer wallportion 252 to the inner wall portion 254 to define a plurality ofcavities 256. While the cavities may extend across the entire axiallength of the collet member 250, in the illustrated embodiment, a radialwall 257 is provided on a first axial side of the collet body 251, todefine a closed end of the cavities 256. When used, for example, in anorbital weld fixture, this closed condition may be desirable forcontainment of the weld gases during the welding operation. In theillustrated embodiment, the radial wall 257 is disposed on the exteriorside (i.e., opposite the weld side) of the collet member 250, in axialalignment with the outer flange 258. Additionally or alternatively, theradial wall 257 may provide further rigid reinforcement for the colletmember 250 during clamping. In other embodiments (not shown), the radialwall may be disposed on the interior side (i.e., the weld side) of thecollet member, for example, to reduce the volume to be filled by theweld gas. In still other embodiments, as shown in FIGS. 14 and 15 anddiscussed in greater detail below, radial walls may be provided on bothaxial sides of the collet body, for example, to provide additionalreinforcement, such that the cavities are fully enclosed between thefirst and second radial walls. Fabrication of an enclosed cavity colletmember may be facilitated by the use of additive manufacturingtechniques, such as, for example, the techniques described in greaterdetail above.

While the inner wall portion 254 of the collet body may provide asemi-cylindrical workpiece engaging surface 254 a, as shown in FIG. 3,in other embodiments, the inner wall portion may include one or moreradially inward extending protrusions sized and positioned to reduce thecontact surface between the collet member and the workpiece. FIG. 4illustrates an exemplary collet member 350 having a collet body 351 withan inner wall portion 354 having a plurality of radially inwardextending protrusions 354 a defining a reduced workpiece engagingsurface, for example, to reduce heat transfer between the workpiece andthe collet member 350. These protrusions may, but need not, comprise adifferent material or material property than the intermediate and/orouter portions of the collet body 351, for example to provide a reducedthermal conductivity (as described above), increased elasticity,improved corrosion behavior, and/or allowance for variations indimension or shape of the workpiece engaging protrusions. As shown, theprotrusions 354 a may extend the entire axial length of the colletmember 350. Alternatively, as shown in FIG. 13, the protrusions may benotched or gapped to further reduce engaging surfaces. As shown in FIGS.11-13, similar protrusions may be provided on the outer wall portions,for example, to reduce surface contact between the collet member and thecollet clamping block.

In the collet members 250, 350 of FIGS. 3 and 4, the radially extendingfastener bore 259, 359 intersects one of the ribs 255, 355, for example,to facilitate positioning and alignment of the installed fastener (notshown) when affixing the collet member 250, 350 to the clamping block.In another embodiment, a hollow fastener boss may be formed between theinner wall portion and the outer wall portion of a collet member, forexample, to retain and guide the fastener when affixing the colletmember to a clamping block. This fastener boss may intersect one of theradially extending members, for example, for further reinforcement. FIG.5 illustrates an exemplary collet member 450 having a collet body 451with a hollow fastener boss 459 a defining the fastener bore 459 andextending between the outer and inner wall portions 452, 454 andintersecting one of the radially extending ribs 455.

While the collet ribs described herein may form substantially solid,plate-like extensions between the inner and outer wall portions of acollet, in other embodiments, one or more of the ribs may be providedwith one or more cutouts, for example, to further reduce the materialmass of the collet member and/or to provide additional cavities or airgaps in the collet member that impede thermal conduction, therebyreducing the heat transfer away from a fixtured workpiece. These cutoutsmay produce a lattice pattern in the ribs, which may be configured tofacilitate fabrication using additive manufacturing techniques, forexample, by allowing both the internal and external surfaces of thecollet to be self-supporting, and/or by enhancing mechanical strength orsupport for the component.

FIGS. 11-13 illustrate exemplary collet members 1050, 1150, 1250including a collet body 1051, 1151, 1251 similar to the collet bodies251, 351, 451 of FIGS. 3-5, with openings, apertures, or cutouts 1060,1160, 1260 formed in the ribs 1055, 1155, 1255 to provide a latticepattern in the ribs. In the embodiments of FIGS. 11 and 12, the cutouts1060, 1160 are diamond-shaped and arranged to provide rigid,intersecting solid walls arranged for enhanced mechanical strength, andfor manufacturability using 3D printing or other additive manufacturingtechniques. In the embodiment of FIG. 13, the cutouts 1260 are radiallyextending ovals arranged to provide radially extending walls that widenat the ends, which also provides for enhanced mechanical strength, andfor manufacturability using 3D printing or other additive manufacturingtechniques.

According to another aspect of the present disclosure, openings orlattice patterns in the collet ribs may also facilitate circulation ofcooling fluid through the weld collet member to decrease the thermaltransfer from the workpiece to the fixture block. In one suchembodiment, as shown in FIGS. 14 and 14A, an enclosed (e.g., by radialwalls 1357, 1367 and non-apertured endmost ribs 1355), at leastpartially hollow collet member 1350 may include cooling fluid ports 1357a in one or both radial end walls 1357, 1367, positioned to allow forthe passage of cooling fluid (e.g., air, nitrogen, argon, water, orother cooling gases or liquids) through openings 1360 in the ribs 1355.In other embodiments, as shown in FIG. 15, the ribs may be replaced by,or supplemented with, axially extending reinforcing structures (e.g.,reinforcing rods 1465, as shown) that provide axial bracing orreinforcement of the collet member 1450, while permitting the passage ofcooling fluid through the hollow collet member. The selected rib latticepattern, and/or shape and arrangement of the supporting rods may provideincreased surface area for contact with the cooling fluid.

To further facilitate thermal transfer from the collet body to thecooling fluid, the support structure(s) of the collet body intermediateportion (e.g., ribs and/or rods) may be formed from a material having agreater thermal conductivity, compared to the inner and outer wallportions of the collet body. For example, the support structure(s) maybe formed with a smaller porosity, or from a greater thermalconductivity metal, such as stainless steel, aluminum and its alloys,copper and its alloys such as brass and bronze, or any suitable materialhaving a higher thermal conductivity (e.g., greater than 20 W/mK), whilethe inner and outer wall portions may be formed with a greater porosity,or from a smaller thermal conductivity material, such as Hastelloy C andX, Inconel alloy 625 and 718, and Monel alloy 400 and K-500, cobalt-basealloys such as Haynes 25 and CoCr derivatives, or any suitable materialhaving a relatively low thermal conductivity (e.g., less than 20 W/mK).

Additive manufacturing techniques for fabricating collet members, asdescribed herein, may additionally be used to fabricate special,customer specific colleting configurations, for example, withoutrequiring expensive and time-consuming casting processes. Thesetechniques may be used, for example, to produce collet members havingalternative geometries. For example, FIGS. 6 and 7 each illustrate anexemplary collet member 550, 650 having a modified inner diameter orinner workpiece engaging portion 554, 654, for example, to provideclearance for a non-cylindrical outer portion of a workpiece (e.g., aflange or other radial extension). In the exemplary embodiment of FIG.6, a radially extending lip 554 a is provided to engage the workpiece,providing radial clearance between the lip and the surface of the innerwall portion 554. In the exemplary embodiment of FIG. 7, a radiallyrecessed groove 654 a in the inner wall portion 654 provides clearancefor a radially extending portion of the workpiece. As another example,FIG. 8 illustrates an exemplary collet member 650 having a modifiedouter wall portion 752 (e.g., with cone shaped extension 752 a), forexample, to axially extend the collet body 751 to provide an axiallyextended inner wall portion 754 without extending the clamping blockengaging portion of the outer wall portion. As another example, FIG. 9illustrates a collet member 850 having an inner wall portion 854defining a non-cylindrical workpiece engaging surface (as shown, ahex-shaped surface, but other shapes and contours may be provided). FIG.10 illustrates a different type of collet member 950, having anon-cylindrical outer wall portion 952.

The inventive aspects have been described with reference to theexemplary embodiments. Modification and alterations will occur to othersupon a reading and understanding of this specification. It is intendedto include all such modifications and alterations insofar as they comewithin the scope of the appended claims or the equivalents thereof.

We claim:
 1. A collet member for a colleting fixture, the collet membercomprising: a monolithic collet body including a clamping block engagingouter wall and a workpiece engaging inner wall extendingcircumferentially between first and second end walls, each of the outerwall, the inner wall, and the first and second end walls extendingaxially between first and second radial walls to enclose at least oneinternal cavity.
 2. The collet member of claim 1, further comprisingfirst and second cooling fluid ports for supplying cooling fluid to theat least one internal cavity.
 3. The collet member of claim 2, whereinthe first and second cooling fluid ports are disposed in at least one ofthe first and second radial walls.
 4. The collet member of claim 1,further comprising one or more support structures extending axially fromthe first radial wall to the second radial wall.
 5. The collet member ofclaim 4, wherein the one or more support structures extend radially fromthe inner wall to the outer wall to define a plurality of internalcavities within the collet body.
 6. The collet member of claim 5,wherein each of the one or more support structures includes at least oneaperture to permit fluid flow between the plurality of internalcavities.
 7. The collet member of claim 5, wherein each of the one ormore support structures includes an apertured lattice pattern.
 8. Thecollet member of claim 4, wherein the one or more support structurescomprises a plurality of axially extending rods.
 9. The collet member ofclaim 1, further comprising one or more support structures extendingradially from the inner wall to the outer wall.
 10. The collet member ofclaim 1, wherein the at least one internal cavity defines a flow pathbetween the first and second cooling ports.
 11. The collet member ofclaim 1, wherein the outer wall comprises a semi-cylindrical outer wall.12. The collet member of claim 1, wherein the inner wall comprises asemi-cylindrical inner wall defining a semi-cylindrical workpieceengaging surface.
 13. The collet member of claim 1, wherein the innerwall comprises a plurality of radially inward extending protrusionsdefining a plurality of discrete workpiece engaging surfaces.
 14. Thecollet member of claim 1, wherein the outer wall comprises a pluralityof radially outward extending protrusions defining a plurality ofdiscrete clamping block engaging surfaces.
 15. The collet member ofclaim 1, further comprising a hollow fastener boss extending from theouter wall to the inner wall.
 16. The collet member of claim 15, whereinthe collet body comprises a plurality of rigid, radially extendingmembers extending between the outer wall and the inner wall to define aplurality of cavities, wherein one of the plurality of radiallyextending members is intersected by the hollow fastener boss.
 17. Acolleting fixture comprising: first and second clamping blocks; andfirst and second collet members secured to corresponding ones of thefirst and second clamping blocks, with the first and second clampingblocks being joinable such that the first and second collet memberstogether define a workpiece engaging collet; wherein at least one of thefirst and second collet members comprises a monolithic collet bodyincluding a clamping block engaging outer wall and a workpiece engaginginner wall extending circumferentially between first and second endwalls, each of the outer wall, the inner wall, and the first and secondend walls extending axially between first and second radial walls toenclose at least one internal cavity.
 18. The colleting fixture of claim17, wherein the one of the first and second collet members comprises oneor more support structures extending axially from the first radial wallto the second radial wall.
 19. The colleting fixture of claim 17,wherein the one of the first and second collet members comprises firstand second cooling fluid ports for supplying cooling fluid to the atleast one internal cavity.
 20. A method of clamping a workpiece for awelding operation, the method comprising: securing first and secondcollet members to first and second clamping blocks; joining the firstand second clamping blocks such that the first and second collet memberstogether define a workpiece engaging collet, wherein at least one of thefirst and second collet members comprises a monolithic collet bodyincluding a clamping block engaging outer wall and a workpiece engaginginner wall extending circumferentially between first and second endwalls, each of the outer wall, the inner wall, and the first and secondend walls extending axially between first and second radial walls toenclose at least one internal cavity; engaging the workpiece betweeninner walls of the first and second collet members; and circulating acooling fluid through the at least one internal cavity of the at leastone of the first and second collet members.